Posted
by
ScuttleMonkey
on Monday May 25, 2009 @05:18PM
from the please-include-armament-instructions dept.

Shojun writes "I am very interested in building my own UAV. Not just one that can fly around happily, but one that I can program to say, take photos every second as it does a barrel roll under a bus (ok, that part may be a pipe dream). I have enough embedded programming experience — it's the hardware which I'm uncertain about. I can go the kit way, and then build the remaining stuff, or get some Dollar Tree Foam boards and build it all. I'm in favor of ease, however. Once the plane is built, buying a dev board seems like a possibility, but I wonder whether it's overkill. Alternatively, if there was a How-to-build example on the net for such an activity that I could adapt, to the degree that I could then program in even completely hardcoded flight instructions, I can certainly take it from there. Thoughts? Has anyone here tried something like this before?"

From your post you clearly know nothing about r/c aircraft. Learn to fly an r/c aircraft well without crashing. Go find a club and an instructor who'll teach you. Also get hold of a good simulator unless you want to spend thousands. That'll take you at least 6 months, probably closer to a year. (Longer if you don't have any aptitude for it). Flying r/c planes takes more practice and skill than you might think. It'll also cost more than you think. Once you have an appreciation for the difficulties of flying R/C you might stand half a chance programming one with a robotic interface. You'll also want to be able to take over manually from time to time when you're programming the thing so if you get something slightly wrong you've got some chance of saving it.

You could also learn about the robotics more simply with an r/c car. R/c cars can move slowly without any risk of falling out of the sky. Some of what you learn will translate to air, other parts won't.

If you want something off the shelf, I did read about robotised r/c helicopters for commercial applications like security but I think they cost in the 10's of thousands. I think you STILL need to know how to take over manually.

The Feds? No. Even the Feds don't have the power to stop a populace from flying their UAVs. Shooting down a model plane is more dangerous than the plane itself, so I don't see it becoming practice. What you are going to see is laws prohibiting *ownership* of UAVs and parts to build them. Most likely, these will come under the blanket of anti-terrorism laws.

I have thought about doing a similar project for a long time, one where you can just enter GPS coordinates at get the plane to fly to those coordinates and take a picture, maybe take some weather readings as well, and send it back to a base station. A big problem that I see would be that it's hard to know how much a finished board would weigh, and how much power consumption would the instruments impose on the battery pack? Would I get an advantage from a more powerful engine from more lift, or would it just lead to power waste for the sake of a bit of extra speed?
I'd also need to know that I have enough lift from the planes wings to carry the UAV circuit too or else it will be bogged down or not fly at all. The project seems to be more mech eng heavy than I'd like to take on as an elec techy.

I'd make sure the Feds have no problem with you running something like this around. Best to make sure you won't get shot down/at.

People fly R/C all the time. There are clubs world wide and there are governing bodies which regulate a wide variety of things - where you can fly, how large your model can be without needing to be certified, what radio frequencies are permitted. What he's describing is more complex than R/C but there won't be much additional regulation to comply with and the "Feds" won't be interested unless he does something that violates the existing laws.

It seem like the obvious approach would be a fairly large RC plane and mount a second the camera (perhaps on a servo) and a tv transmitter on it. You downlink the video to a laptop that then uses some sort of usb connection to a gutted rc controller, either with servos moving the sticks directly, or better yet, bypassing the potentiometers and variably outputting voltage directly to the control board.

It seems like the hardest thing is avoiding (auto)pilot error. I don't have any experience with RC planes, but from what I've heard you have to go into with the attitude that you're going to spend a thousand dollars for 10 seconds of entertainment. You just have to assume that the plane is going to be destroyed on its first flight. Anything after that is bonus.

Absolutely. I know several groups who have had great difficulty getting helicopter UAVs working (including my own!), and these were major government-funded research organisations. If building a UAV is on the cards do yourself a favour and start with a fixed-wing vehicle. You can use cheap sensors without worrying excessively about more advanced topics like state estimation and gyro bias calibration and drift. WYIAAARSIH (Why Yes, I Am An Aero-Roboticist Specialising In Helicopters).

Yeah, the FAA has a system in place to introduce new UAVs in a legal fashion. Unfortunately, the current system requires that every new UAV go through this process. My company has been on the waiting list for ~2 years to have our UAV made legal. They specifically told us that they will only certify 4 UAVs per year, and they will give priority to "established" companies. Basically, Boeing or Northrup Grumman can get their UAVs certified, but a startup company has no chance.

New regulations are just around the corner -- it will establish rules like, "if the vehicles weighs X lbs and has an engine smaller than Y, then you can fly in Class G airspace". It will create defined categories, so it won't be necessary to certify on a per vehicle basis anymore.